Montrice Marquel Gibson of York has been arrested and another man, Tysheem Devier Santiago, is being sought.

Stefen Dion Simmons had just gotten out of York County Prison on Friday, serving nearly a year for a charge of receiving stolen property.

The 20-year-old and his younger brother wanted to celebrate. According to Pennsylvania State Police in charging documents, the two turned to social media.

The next day, the brothers posted photos online of jewelry and cash.

"He (Simmons' brother) stated they did this in the hope that someone would see the post and want to hang out with them to celebrate," according to charging documents.

At some point after they posted the photos, they had some takers to their proposition. A female juvenile and Montrice Marquel Gibson, 25, who also went by the names "Trell" and "Monti," were interested in hanging out.

The group later grew by two, as Gibson's brother, Christopher Gibson, 18, and Tysheem Devier Santiago, 18, joined them before the brothers were picked up.

In a news release, state police referred to the group as "acquaintances" of the brothers.

Arrangements were made for Simmons and his brother to be picked up near their Chanceford Township home on Sunday night.

The two face murder of the first, second and third degree in the shooting death of Simmons. They also are charged with robbery and conspiracy to commit robbery.

Santiago has additional charges of theft and receiving stolen property, according to a warrant filed at District Judge John H. Fishel's office.

In a news release, state police said the robbery was planned.

Masked man

On Sunday night, Simmons and his brother were waiting near their Chanceford Township home when the red sedan passed them, continued down the road, then pulled up behind them.

They got in.

The female juvenile was at the wheel, with Montrice and Christopher Gibson inside. She only drove a short distance before she stopped and rolled the windows down.

From the shadows, a man in a mask — later identified as Santiago — armed with a gun, walked up to where Simmons was seated inside the car

He struck Simmons in the head and demanded money from him. Santiago shot Simmons and dragged his body from the car, throwing him on the ground.

Montrice Marquel Gibson(Photo: Submitted)

Santiago turned his attention to Simmons' brother, demanding money from him, but the juvenile said he had none.

Santiago climbed into the front passenger seat and the female driver said words to the effect of, "If you are not my blood, get the ---- out of the car!"

Simmons' brother got out and went over to his older brother, who was lying in the front yard of a home on Oriole Circle. As the red sedan took off, he went to the home for help and to call 911.

Police gather clues

State police were able to connect with Christopher Gibson and interviewed him Monday at their barracks in Loganville.

Christopher Gibson said that he, the female juvenile, his brother and Santiago left for Chanceford Township from his brother's home on East Poplar Street in York.

Once they reached the area near Oriole Court, they dropped off Santiago before picking up Simmons and his brother. Then, once the brothers were inside the car, the group returned to where Santiago was waiting.

Christopher Gibson said he heard gunshots and that in a struggle between Santiago and Simmons, Santiago may have shot himself in the shoulder.

Santiago rummaged through Simmons' pockets, taking his wallet, after he pulled his body from the car, Christopher Gibson said.

Stefen Simmons, 20.(Photo: Submitted)

The group returned to Montrice Gibson's home, where everyone got out, except for Christopher Gibson, who first drove to his home and then to Dallastown High School, where he parked the vehicle.

Police found the car, a 2007 red Ford Focus, at the high school and traced it back to a Springfield Township address where Christopher Gibson and the female juvenile live.

State police also interviewed the female juvenile, who said she drove the car that night and also identified Santiago as the man who shot Simmons.

Christopher Gibson also picked Santiago out of a photo line-up, identifying him as the man who shot Simmons.

How to help

Anyone with any information on Santiago's whereabouts is asked to contact Pennsylvania State Police at 717-428-1011.